21591+6400
- Unique Name: 21591+6400HU 975AB
- RA: 21 59 03.72
- Dec: +63 59 55.3
- Discoverer: HU
- Discoverer Number: 975
- Components: AB
- First year: 1904
- Last year: 2008
- Observations: 12
- First position angle: 214
- Last position angle: 210
- First separation: 0.3
- Last separation: 0.3
- Mag first component: 9.39
- Mag second component: 10.04
- Spectral type: B8V
- Primary proper motion RA: -4
- Primary proper motion DEC: -8
- Secondary proper motion RA:
- Secondary proper motion DEC:
- Durchmusterung: +63 1794
- Notes: